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ykaes.c
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ykaes.c
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/* ykaes.c --- Implementation of AES-128.
*
* Copyright (c) 2006-2013 Yubico AB
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "yubikey.h"
#define NUMBER_OF_ROUNDS 10
static const uint8_t RC[] =
{ 0x1, 0x2, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36 };
static const uint8_t rijndael_sbox[] = {
0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5,
0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0,
0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC,
0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A,
0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0,
0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B,
0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85,
0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5,
0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17,
0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88,
0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C,
0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9,
0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6,
0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E,
0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94,
0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68,
0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
};
static const uint8_t rijndael_inv_sbox[] = {
0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38,
0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87,
0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D,
0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2,
0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16,
0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA,
0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A,
0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02,
0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA,
0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85,
0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89,
0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20,
0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31,
0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D,
0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0,
0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26,
0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
};
static inline uint8_t
xtime (uint8_t b)
{
return (b & 0x80) ? ((b << 1) ^ 0x1b) : (b << 1);
}
void
yubikey_aes_decrypt (uint8_t * state, const uint8_t * key)
{
uint8_t i, j, round_key[0x10];
uint8_t a02x, a13x;
uint8_t a02xx, a13xx;
uint8_t k1, k2;
memcpy (round_key, key, sizeof (round_key));
for (i = 0; i < NUMBER_OF_ROUNDS; i++)
{
round_key[0] ^= RC[i];
round_key[0] ^= rijndael_sbox[round_key[13]];
round_key[1] ^= rijndael_sbox[round_key[14]];
round_key[2] ^= rijndael_sbox[round_key[15]];
round_key[3] ^= rijndael_sbox[round_key[12]];
for (j = 4; j < 16; j++)
round_key[j] ^= round_key[j - 4];
}
for (i = 0; i < 0x10; i++)
state[i] ^= round_key[i];
for (i = 1; i <= NUMBER_OF_ROUNDS; i++)
{
/* First row: 0 shift, 0 4 8 12 */
state[0] = rijndael_inv_sbox[state[0]];
state[4] = rijndael_inv_sbox[state[4]];
state[8] = rijndael_inv_sbox[state[8]];
state[12] = rijndael_inv_sbox[state[12]];
/* Second row: -1 shift, 1 5 9 13 */
j = state[13];
state[13] = rijndael_inv_sbox[state[9]];
state[9] = rijndael_inv_sbox[state[5]];
state[5] = rijndael_inv_sbox[state[1]];
state[1] = rijndael_inv_sbox[j];
/* Third row: -2 shift, 2 6 10 14 */
j = state[2];
state[2] = rijndael_inv_sbox[state[10]];
state[10] = rijndael_inv_sbox[j];
j = state[6];
state[6] = rijndael_inv_sbox[state[14]];
state[14] = rijndael_inv_sbox[j];
/* Fourth row: -3 shift, 3 7 11 15 */
j = state[3];
state[3] = rijndael_inv_sbox[state[7]];
state[7] = rijndael_inv_sbox[state[11]];
state[11] = rijndael_inv_sbox[state[15]];
state[15] = rijndael_inv_sbox[j];
for (j = 15; j > 3; j--)
round_key[j] ^= round_key[j - 4];
round_key[0] ^=
(RC[NUMBER_OF_ROUNDS - i] ^ rijndael_sbox[round_key[13]]);
round_key[1] ^= rijndael_sbox[round_key[14]];
round_key[2] ^= rijndael_sbox[round_key[15]];
round_key[3] ^= rijndael_sbox[round_key[12]];
for (j = 0; j < 16; j++)
state[j] ^= round_key[j];
if (i != NUMBER_OF_ROUNDS)
{
for (j = 0; j < 16; j += 4)
{
k1 = state[j] ^ state[j + 2];
a02x = xtime (k1);
k2 = state[j + 1] ^ state[j + 3];
a13x = xtime (k2);
k1 ^= (k2 ^ xtime (state[j + 1] ^ state[j + 2]));
k2 = k1;
a02xx = xtime (a02x);
a13xx = xtime (a13x);
k1 ^= (xtime (a02xx ^ a13xx) ^ a02xx);
k2 ^= (xtime (a02xx ^ a13xx) ^ a13xx);
state[j] ^= (k1 ^ a02x);
state[j + 1] ^= k2;
state[j + 2] ^= (k1 ^ a13x);
state[j + 3] ^= (k2 ^ a02x ^ a13x);
}
}
}
}
/*******************************************************************
function aesEncrypt encrypts a single AES-128 block
void aesEncrypt(unsigned char *state, const unsigned char *key)
Where:
"state" is state buffer, i.e. plaintext in, ciphertext out
"key" is pointer to AES key
*************************************************************************/
void
yubikey_aes_encrypt (uint8_t * state, const uint8_t * key)
{
unsigned char i, j, k, tmp, round_key[0x10];
memcpy (round_key, key, sizeof (round_key));
for (i = 0; i < 16; i++)
state[i] ^= key[i];
for (i = 0; i < NUMBER_OF_ROUNDS; i++)
{
/* First row: 0 shift, 0 4 8 12 */
state[0] = rijndael_sbox[state[0]];
state[4] = rijndael_sbox[state[4]];
state[8] = rijndael_sbox[state[8]];
state[12] = rijndael_sbox[state[12]];
/* Second row: 1 shift, 1 5 9 13 */
tmp = state[1];
state[1] = rijndael_sbox[state[5]];
state[5] = rijndael_sbox[state[9]];
state[9] = rijndael_sbox[state[13]];
state[13] = rijndael_sbox[tmp];
/* Third row: 2 shift, 2 6 10 14 */
tmp = state[2];
state[2] = rijndael_sbox[state[10]];
state[10] = rijndael_sbox[tmp];
tmp = state[6];
state[6] = rijndael_sbox[state[14]];
state[14] = rijndael_sbox[tmp];
/* Fourth row: 3 shift, 3 7 11 15 */
tmp = state[15];
state[15] = rijndael_sbox[state[11]];
state[11] = rijndael_sbox[state[7]];
state[7] = rijndael_sbox[state[3]];
state[3] = rijndael_sbox[tmp];
if (i != (NUMBER_OF_ROUNDS - 1))
{
for (k = 0; k < 16; k += 4)
{
j = state[k] ^ state[k + 1];
tmp = j ^ state[k + 2] ^ state[k + 3];
j = xtime (j);
state[k] ^= (j ^ tmp);
j = state[k + 1] ^ state[k + 2];
j = xtime (j);
state[k + 1] ^= (j ^ tmp);
j = state[k + 2] ^ state[k + 3];
j = xtime (j);
state[k + 2] ^= (j ^ tmp);
state[k + 3] = state[k] ^ state[k + 1] ^ state[k + 2] ^ tmp;
}
}
round_key[0] ^= RC[i];
round_key[0] ^= rijndael_sbox[round_key[13]];
round_key[1] ^= rijndael_sbox[round_key[14]];
round_key[2] ^= rijndael_sbox[round_key[15]];
round_key[3] ^= rijndael_sbox[round_key[12]];
for (k = 4; k < 16; k++)
round_key[k] ^= round_key[k - 4];
for (j = 0; j < 16; j++)
state[j] ^= round_key[j];
}
}